DE102014212003A1 - Method of manufacturing an electronic assembly and electronic assembly - Google Patents

Abstract

A method of manufacturing an electronic assembly comprises the steps of providing an electronic component (10) disposed on a support and a cover (2) enclosing the electronic component, pushing the cover onto the support such that an inner surface (6) of a End portion (4) of the lid approximates the electronic component, initiating fusion of the lid with the carrier and applying a compressive force to the carrier to the carrier, measuring a sinking path of the lid into the carrier on an outer surface (8) of the end portion of the lid Cover, and finishing the fusion, when the outer surface of the end portion does not sink, on. The electronic component can be fixed by the cover, wherein an excessive compressive force on the electronic component is avoidable.

Description

The invention relates to a method for producing an electronic structural unit and to an electronic structural unit.

Drive trains of vehicles, which include, for example, transmissions and other devices, usually contain electronic components, such as sensors for detecting movements within mechanical elements, in addition to mechanical elements. Sensors are often very sensitive electronic components, which are to be protected from external influences and are therefore usually encapsulated for such use.

Fully enclosed sensors are often used, which detect the rotation of waves or other rotating machine elements without contact. The encapsulation is carried out by complete, tight enclosure of the electronic component with a housing which consists of a suitable material for protecting the sensor.

A sensor for wireless detection of rotational speeds and other parameters requires the smallest possible distance of an active sensor surface to the relevant machine element, wherein the distance should not exceed a predetermined value as possible. When the sensor is encapsulated, it can be fixed by the housing surrounding it, which on the one hand allows the sensor to be arranged as close as possible to an outer surface of the housing, and on the other hand also necessitates a separate mounting or fixing device. By arranging the outer surface of the housing close to the machine element concerned, the requirement of the small distance can be met.

However, it should be noted that in the encapsulation of the electronic component, the cover must not exert too much force on the electronic component, but at the same time must allow its sufficient fixation. In previously known methods for welding a cover to a carrier of an electronic component can exert too high a force on the electronic component by tolerance deviations of the lid, so that its proper function is compromised, which does not necessarily have to limit to a passed signal.

It may therefore be regarded as an object of the invention to propose a method for manufacturing an electronic component, in which an electronic component is to be fixed by a cover, while at the same time ensuring that the force applied to the electronic component is too high avoid.

The object is achieved by a method having the features of independent claim 1. Advantageous embodiments and further developments can be taken from the subclaims and the following description.

The invention relates to a method for producing an electronic assembly comprising the steps of providing an electronic component mounted on a carrier and a lid enclosing the component, pushing the lid against the carrier such that an inner surface of a closed end portion of the lid contacts the electronic Approaching member, the merging of the lid with the carrier and the simultaneous application of a force to the carrier on the lid, the multiple measuring the Eininkwegs of the lid in the carrier at at least one point of an outer surface of the end portion and terminating the fusion when the Eininkweg remains constant.

This method is suitable for producing an electronic component which has an electronic component which is arranged on a carrier and is encapsulated by a cover and at the same time fixed. By repeatedly measuring the sinking distance, it can be reliably observed to detect when an end portion of the lid abuts and fixes the electronic component.

The carrier is to be understood as a kind of basic body, which is positionable in the vicinity of the machine element to be monitored and can have various shapes that allow its easy attachment. However, the nature of the basic body is not intended to limit the subject matter of the invention. It could be advantageous if the base body and the cover made of the same material or similar materials that allow the fusion of the two components and show a similar thermal expansion behavior.

For merging the lid, which may be designed dome-shaped or approximately flat or disc-shaped depending on the type of carrier, with the base of the lid is placed on the electronic component and rests on the base body, wherein in an initial position, the inner surface of the lid, the electronic Component not yet touched. With the aid of a mask, the lid can be pressed onto the carrier in a fastening region, for example on a circumferential collar. At the same time by the action of a suitable laser beam or by the action of vibrations in the ultrasonic range a Fusion of the two bodies are performed in the material of the lid under the action of a sufficient surface pressure in a joining zone directed to the lid force partially merges with the material of the body in the joining zone and sinks into it. This results in a preferably circumferential seal between the carrier and the lid, so that the electronic component is completely encapsulated.

The carrier or the lid could have a circumferential projection, which comes to rest on the respective other component and penetrates into the respective other component during the fusion. Regardless of the design of the surfaces in question, the lid continuously sinks in the direction of the carrier during the fusion process. Here, the so-called Eininkweg is covered. From a certain sinking path, the inner surface of the end section finally rests on the electronic component.

The lid is still not completely rigid, but the end portion may have a certain elasticity, which helps this to an effective spring stiffness. This may be assisted by a concavity of the end portion which has a predetermined spring stiffness and first contacts the component in the fusion process. By acting on the inner surface of the end portion of one of the sinking opposing force of the usually rigid electronic component, an elastic deformation of the end portion occur, resulting in a visible bulge of the outer surface. Thus, in spite of the progressive sinking action, a location of the outer surface will remain at a constant height relative to the support, i. the sinking path remains constant as soon as the electronic component is fixed by touching the inner surface of the end section. To exert excessive force on the electronic component, the fusion process is terminated upon reaching this point. The force acting on the component is determined solely by the spring geometry of the cover.

A core thus lies in the multiple measurement of a distance between the at least one location of the outer surface and a reference surface of the carrier to observe the sinking path and to initiate the termination of fusing. This at least one location may in particular include an expected vertex of a bulge of the outer surface, which lies in the sinking directly above the electronic component.

With this method, several advantages can be achieved in combination. On the one hand it is ensured that the electronic component is actually fixed by the cover and thus maintains its predetermined position. On the other hand can be ensured by the novel control process that the force on the electronic component to protect the same is limited from mechanical overuse. A fusion between the lid and the carrier can be further improved by the control process, because there are no precautions or safety factors to be considered in the assessment of the sinking still to be performed, which could lead to the fact that the electronic component is not properly fixed, for Others also that the merger process on a revolving path is not yet complete. The distance between an outer surface of the end portion lid and the electronic component is minimal, since no safety clearance is needed. The assembly can thus be made smaller, since tolerances are bridged without the action of a directed force on the component.

In a particularly advantageous embodiment, the measurement of the sinking distance of the lid takes place by an optical distance measurement from a carrier-fixed point. An optical distance measurement can be accomplished by a variety of different devices. These are usually based on the detection of at least one physical quantity of a reflected light beam and in particular of a laser beam which is emitted continuously or pulsed on the outer surface of the lid. The physical quantities to be detected may vary. On the one hand, a transit time measurement between the emission of a light beam and the reception of a reflected light beam can be carried out. By comparing a plurality of successive transit time measurements, it can thus be determined how the transit time and thus the distance between the light source and the outer surface changes. A starting point with an initial running time can be considered as the zero point for a calculation of the sinking time. If the measured running time changes, this leads to a change in the calculated sinking distance. To achieve a higher measurement accuracy, the phase position of the reflected light beam can be examined, for example via a laser interferometry. Here, two or more light bundles are guided on separate optical paths and then brought together again by reflection, which finally leads to an interference pattern that is dependent on the path difference of the light beam. This interference pattern can be examined to determine the distance between a carrier fixed point and the at least one point on the outer surface. The distance measurement can be further achieved by a camera-based method.

The fusion may be further performed by a laser welding method. In the case of laser welding, one of the carrier and the lid can be designed to be laser-transparent, so that irradiation of a connection region through the laser-transparent component results in heat input at an interface to the non-laser-transparent component, which leads to a fusion.

Furthermore, the fusion can also be carried out by an ultrasonic welding process. For this it is not necessary that one of the two components is laser-transparent. In a joint region, high-frequency mechanical vibrations are excited, resulting in molecular and boundary friction in the joint region, which generates the heat necessary for welding. The method is particularly suitable for thermoplastics.

Both methods for fusing the lid and the carrier are characterized by the fact that many different thermoplastic materials can be fused together quickly, safely, with reproducible quality and sorted purity, and furthermore an absolute fluid tightness is achieved.

The connection of the optical measurement of Einsinkwegs with a laser welding method is particularly favorable, because a laser welding device can be equipped with an additional device for optical distance measurement, wherein the welding laser is not hindered. A mechanical displacement or force measurement would collide in a device with a laser beam or a welding mask.

The invention further relates to an electronic assembly, comprising a support with an electronic component arranged thereon and a cover enclosing the electronic component, wherein the cover has an elastic, closed end portion with an inner surface and an outer surface, wherein the inner surface can be brought onto the electronic component in that, when the cover is pressed onto the support, the inner surface of the cover comes into contact with the electronic component and is elastically deformed on the outer surface.

In an advantageous embodiment, one of the carrier and the lid is laser-transparent. This enables a laser welding process, in particular for thermoplastics.

In an equally advantageous embodiment, the lid and the carrier are adapted to be welded together by means of an ultrasonic welding process. The carrier and the lid are in particular made of a thermoplastic material.

Other features, advantages and applications of the present invention will become apparent from the following description of the embodiments and the figures. In the figures, the same reference numerals for the same or similar objects.

1 shows an end portion of a lid in a movement on an electronic component in a sectional view.

2 shows the inner surface of the end portion on the electronic component.

3 shows a course of a sinking during a merge operation in a diagram.

In 1 becomes a lid 2 for covering an electronic component 10 shown having a closed end section 4 which, after performing the method according to the invention on the component 10 should rest. The material of the lid 2 is elastic and the end section 4 is designed such that a predetermined spring geometry is formed in a sinking x.

In 1 is the end section 4 still completely unloaded. An inner surface 6 of the lid 2 is due to the selected spring geometry as a bulge to the electronic component 10 directed, which with the lid 2 to be encapsulated. This condition could be at the beginning of a fusion process where the lid 2 rests on a support, not shown here and the electronic component 10 not touched yet.

When merging the lid 2 and the carrier, wherein material of the lid 2 merges with the material of the carrier, the electronic component 10 from a certain sinking of the lid 2 touched in the carrier.

In 2 It is shown that when touching the component 10 this a drag on the inner surface 6 exerts, so that the end section 4 bulges outwards. This will create an outer surface 8th of the lid 2 deformed.

By watching a spot 12 of the lid 2 , which is about a vertex of the outer surface 8th may be by means of an optical device for detecting a distance d to a carrier-fixed point 14 can be recorded when the body 12 the sinking in of the lid 2 no longer follows in the carrier, but because of the rigid component 10 remains on an end position, ie a constant Einsinkweg.

By choosing the spring geometry can on the component 10 applied force, which results solely from the travel and the spring constant, are set very accurately.

3 shows in a diagram a course of one of a device for optically measuring the Einsinkweges of the site 12 recorded eininkweges. About a free sinking section 16 the lid sinks 2 in the direction of the carrier, without the electronic component 10 is touched. From the touch of the electronic component 10 the outer surface moves 8th not anymore, because the inner surface 6 on the electronic component 10 rests. Here the lid sinks 2 no longer in the carrier, but the component 10 pushes against the inner surface 6 , Consequently, in a fixing section 18 from the outside surface 8th no distance traveled and it can thus be concluded that the electronic component 10 from the inner surface 6 is held and a welding process can be canceled. After termination of the merger process is still a maximum Nachdrückweg about the spring geometry deformed, so that the force acting on the component 10 which corresponds to the spring force.

Claims (9)

Method for producing an electronic component, comprising the steps of providing an electronic component ( 10 ) and one the electronic component ( 10 ) enclosing lid ( 2 ), - slipping on the lid ( 2 ) on the support such that an inner surface ( 6 ) of an end section ( 4 ) of the lid ( 2 ) the electronic component ( 10 ), initiating a fusion of the lid ( 2 ) with the carrier and applying to the carrier directed pressure force on the lid ( 2 ), - measuring a sinking of the lid ( 2 ) in the carrier on an outer surface ( 8th ) of the end section ( 8th ) of the lid, ( 2 ) and - stopping the fusion when the outer surface ( 8th ) of the end section ( 4 ) no longer sinks. The method of claim 1, wherein measuring the sinking distance of the lid ( 2 ) by an optical distance measurement of a carrier fixed point ( 14 ). The method of claim 2, wherein the optical distance measurement based on a transit time measurement of a light beam or on an interferometry. Method according to one of the preceding claims, wherein the fusion is carried out by a laser welding process. Method according to one of claims 1 to 3, wherein the fusion takes place by an ultrasonic welding process. Electronic assembly comprising a support with an electronic component ( 10 ) and one the electronic component ( 10 ) enclosing lid ( 2 ), the lid ( 2 ) an elastic, closed end portion ( 4 ) with an inner surface ( 6 ) and an outer surface ( 8th ), wherein the inner surface ( 6 ) on the electronic component ( 10 ) is placed so that when pressing the lid ( 2 ) on the support the inner surface ( 6 ) of the lid ( 2 ) with the electronic component ( 10 ) and on the outer surface ( 8th ) is elastically deformed. Electronic assembly according to claim 6, wherein one of the carrier and the lid ( 2 ) laser-transparent. Electronic assembly according to claim 6, wherein the lid ( 2 ) and the carrier are adapted to be fused together by an ultrasonic welding process. Electronic assembly according to one of claims 6 to 8, wherein the lid ( 2 ) in the end section ( 4 ) has a concavity.

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